The nefarious Georgina (Michelle Trachtenberg) is back, and she's up to something — or at least she wants you to think so, in which case she probably is — on the third-season finale of the teen soap “Gossip Girl.” (KTLA, 9 p.m.)

TUESDAY

On “Frontline,” a look at the effects of post-traumatic stress disorder and combat injuries on U.S soldiers returning from Iraq includes the case of Jose Barco, once hailed a hero and now serving a 52-year prison sentence for attempted murder. (KCET, 9 p.m.)

WEDNESDAY

Heartthrob alert! Nick Jonas of the tween-pleasing Jonas Brothers is one of several celebs attempting to fool unsuspecting fans by posing as their own doppelgängers on a new installment of the hidden-camera show “I Get That a Lot.” (CBS, 8 p.m.)

THURSDAY

As much as we loved “The X-Files,” the super-geeky sci-fi drama “Fringe” boldly goes where that series never did: specifically, an alternate universe. Anna Torv and Leonard Nimoy star in the second-season finale. (Fox, 9 p.m.)

FRIDAY

It's a matter of life and death — wait, isn't it always? — for Melinda (Jennifer Love-Hewitt) on the season finale of “Ghost Whisperer,” and likewise for Allison (Patricia Arquette) on the “Medium” season finale. (CBS, 8 and 9 p.m.)

SATURDAY

O Danny Bhoy, the pipes, the pipes are calling: The comic, fast becoming a global phenom, trots out his fine Scottish brogue and a few other accents in the special “Subject to Change: Danny Bhoy.” (Comedy Central, 11 p.m.)